Kober 5BB

History of Origin and Economic Significance

The grape rootstock Berlandieri x Riparia Kober 5BB has a hybrid origin. The breeding process was initiated by the Hungarian breeder Teleki, who performed the sowing of Vitis berlandieri seeds, presumably obtained from open pollination by Vitis riparia pollen. The selection of seedlings was carried out in groups based on similar morphological traits. Later, Austrian breeder F. Kober continued individual clonal selection within the breeding numbers established by Teleki, fixing the combination under the name Berlandieri x Riparia Kober 5BB.

The Kober 5BB variety has gained wide commercial distribution. In the Moldavian SSR, by 1960, the proportion of this rootstock in mother plantations reached 22.4% (about 4 million vines). In the Georgian SSR, the variety took first place in terms of cultivation area, covering approximately 600 hectares of mother plantations. In Ukraine, the rootstock areas amounted to about 120 hectares. The grape rootstock Berlandieri x Riparia Kober 5BB is officially zoned in Moldova, Ukraine, and Georgia; it is recommended for the Transcarpathian region, calcareous soils of Transnistria, and viticultural regions with stable winter snow cover.

The main advantage of the rootstock variety Berlandieri x Riparia Kober 5BB is its high resistance to carbonate soils. The variety tolerates a total soil lime content within 30–40% and more, having an index of 20 according to the Drouineau-Galet scale, which allows its successful application on highly calcareous lands in Georgia and Transnistria, where less resistant rootstocks (such as 101-14) suffer severely from chlorosis. However, on excessively rich chernozem-like soils with a low content of calcium carbonate (15–20%), cases of scion chlorosis were recorded in certain years.

The influence of the rootstock on scion components is characterized by the stimulation of vigorous vegetative growth. The root system of the Kober 5BB variety is deep and powerful, which provides stable vine nutrition under conditions of moderate drought on fertile, non-drying soils. At the same time, during critically dry periods (for instance, in 1946), plantations on this rootstock demonstrated a worse condition and a higher rate of vine mortality compared to the 101-14 rootstock. A significant disadvantage of the rootstock on rich soils of Moldova is that the Kober 5BB variety significantly lags behind the scion in radial trunk thickening. In Shasla and Fetyaska varieties, this thickening imbalance manifests by the 6th–8th year after planting, causing gradual vine mortality. Plantations on this rootstock fruit most intensively and highly productively predominantly at a young age.

Morphological Description of the Rootstock Variety Berlandieri x Riparia Kober 5BB

The botanical description of organs and cane elements was compiled in the variety testing plots of the Moldavian Research Institute of Horticulture, Viticulture, and Winemaking:

• Young shoot (tip): the apex of the growing shoot is colored green with a faint reddish tint along the edges of the lobes and bears intensive grayish-white pubescence. Young leaves are almost entire, folded in a groove-like shape, and have a characteristic bronze tint. The upper side of the young leaf is covered with rather dense cobwebby pubescence, while the lower side bears bristles along the veins. The apical part of the shoot axis and the petioles of young leaves are also noticeably pubescent.
• Mature leaf: has a large size, rounded shape, weakly marked three lobes, and a dense leathery texture. The leaf blade is flat or slightly grooved; the upper surface is dark green and slightly bullate. The main veins have a faint violet-red tint at the very base. The lower side of the blade is characterized by sparse cobwebby pubescence and bristles located along the veins.
• Sinuses and teeth of the leaf: the upper lateral sinuses are weakly developed, expressed as an incoming angle or barely outlined; the lower sinuses are completely absent. The petiole sinus is open, lyre-shaped or V-shaped with a sharp base. The teeth at the ends of the lateral lobes are triangular and slightly elongated; the tooth at the end of the central lobe is distinctly elongated. The marginal teeth are wide-triangular, almost dome-shaped, slightly inclined, with a pointed apex and characteristic white points at the tips. The petiole is shorter than the midvein of the leaf, colored dark green with a faint lilac-red tint, bearing sparse cobwebs or bristles in places.
• Mature shoot: the annual cane is thick, with long internodes (up to 15–17 cm), colored grayish-brown. The surface of the shoot is ribbed. A feature of the anatomical structure is relatively loose wood and a large pith, the diameter of which is 0.4–0.5 of the total shoot diameter. The number of formed lateral shoots (suckers) is insignificant.
• Reproductive organs: the flower type is functionally female, the stamens are bent outwards, and the anthers are turned down. The inflorescences are small in size and loose. The formed bunch is small, cylindrical-conical, and loose in structure. The berries are very small, rounded, and acquire a bluish-black tint when fully mature. Inside, the berries contain 3–4 small rounded seeds.

Features of Agricultural Practices in Nursery Production

The grape rootstock Berlandieri x Riparia Kober 5BB is characterized by increased heat requirements. In the conditions of Moldova and the south of Ukraine, bud break on short-armed training systems begins in mid-April, which is 3–5 days later than in Riparia Gloire. Flowering occurs at the end of May — 8–10 days later than in the 101-14 variety. The Kober 5BB variety possesses high growth vigor: with a daily cane growth of up to 14–16 cm and a vine load of 16–20 shoots, the total length of the annual growth of a vine is 80–100 meters (reaching up to 120 meters in individual vines), and the length of single canes reaches 4–5 meters, sometimes up to 12–14 meters.

Wood ripening begins in the first decade of August. In the initial period, the rate of lignification lags behind the indicators of the 101-14 rootstock, but under a favorable temperature regime in late summer and early autumn, the rate accelerates, and by the end of September, the indicators level out. In dry and warm autumn, the mature part of the cane constitutes 75–85% of the total length of the annual growth. To improve cane quality in the south of Moldova, shoot topping is carried out in the second to third decade of July, and phosphorus-potassium fertilizers are applied, which ensures uniform growth, good wood ripening along the entire length, and increases the yield of first-grade rootstocks from the nursery field by 15–18%.

The productivity of mother plantations is very high. With a short-armed training system, a planting density of 2000 vines/ha, and a shoot load of 18–25 per vine, 100–140 thousand half-meter cuttings are harvested per hectare in commercial farms of Moldova and Transcarpathia (up to 150 thousand in experimental plots). In Georgia, the yield is about 95 thousand long cuttings (110 cm) per hectare. The best training systems for mother plantations are recognized as the high four-wire trellis and the low horizontal trellis. Cuttings of the Kober 5BB variety form callus and root well, ensuring a high yield of standard material. Grafting compatibility with European varieties is satisfactory, but the overall affinity in Kober 5BB is slightly lower than in 101-14, 3309, or Riparia Gloire varieties. Sometimes, the yield of rootstocks from the nursery field may decrease due to insufficient maturity of the eyes or frost damage to the vines.

Indicators of resistance to adverse environmental conditions have their own characteristics. The rootstock is practically resistant to mildew and root phylloxera; the susceptibility to the leaf form of phylloxera is inconsistent and generally low. The frost resistance of the Kober 5BB root system is recognized as insufficient: the roots tolerate a soil temperature drop only down to —8...—9 °C, due to which the canes are severely damaged in snowless harsh winters both in mother plantations and in grafted vineyards. For this reason, the Kober 5BB variety is recommended for cultivation in regions with a stable winter snow cover, and when grafting, it is advised to use longer rootstock cuttings (up to 45 cm) and perform deep soil cultivation to stimulate deep root placement. The above-ground part of the vines winters well, but young shoots often suffer from late spring frosts, and immature tips suffer from early autumn cold spells.

*Publisher's note: the ampelographic overview is compiled based on the variety description from the book "Ampelography of the USSR. Little-distributed grape varieties", Volume III, published in 1966. The text has been processed and edited only in terms of formatting, while, for the sake of preserving the authenticity of historically valuable material, the formulations and style of description inherent in the Soviet ampelographic school were not changed.